add readme and thanks to maelbreaker

nebkor-maelstrom/README.md

@@ -0,0 +1,70 @@
+# A synchronous and simple Maelstrom crate
+
+`nebkor-maelstreom` is a lean and simple synchronous library for writing
+[Maelstrom](https://github.com/jepsen-io/maelstrom/tree/0186f398f96564a0453dda97c07daeac67c3d8d7)-compatible
+distributed actors. It has three dependencies:
+
+ - serde
+ - serde_json
+ - serde_repr
+ 
+For a simple example, see the [gg-echo](https://git.kittencollective.com/nebkor/chatty-catties/src/branch/main/gg-echo/src/main.rs) program:
+
+``` rust
+use std::sync::{Arc, Mutex};
+
+use nebkor_maelstrom::{Body, Message, Node, Runner};
+
+struct Echo;
+
+impl Node for Echo {
+    fn handle(&mut self, runner: &Runner, msg: Message) {
+        let typ = &msg.body.typ;
+        if typ.as_str() == "echo" {
+            let body = Body::from_type("echo_ok").with_payload(msg.body.payload.clone());
+            runner.reply(&msg, body);
+        }
+    }
+}
+
+fn main() {
+    let node = Echo;
+
+    let node = Arc::new(Mutex::new(node));
+
+    let runner = Runner::new(node);
+
+    runner.run(None);
+}
+```
+
+## How to use
+
+Create a struct and implement `nebkor_maelstrom::Node` for it, which involves a single method,
+`handle(&mut self, &Runner, Message)`. This method is passed a `Runner` which contains methods like
+`send`, `reply`, and `rpc`.
+
+In your main function, instantiate that struct and wrap it in an `Arc<Mutex<>>`, then pass that into
+`Runner::new()` to get a Runner. The `run()` method takes an optional closure that will be run when
+the `init` Message is received; see the
+[broadcast](https://git.kittencollective.com/nebkor/chatty-catties/src/commit/fff7fdc2d52f7d4c2d4d9c581ea16cdf0e1e3f30/gg-broadcast/src/main.rs#L18-L33)
+program for an example of that, where it spawns a thread to send periodic messages to the node.
+
+## Design considerations
+
+I wanted the client code to be as simple as possible, with the least amount of boilerplate. Using
+`&mut self` as the receiver for the `handle()` method lets you easily mutate state in your node if
+you need to, without the ceremony of `Rc<Mutex<>>` and the like. Eschewing `async` results in an
+order of magnitude fewer dependencies, and the entire workspace (crate and clients) can be compiled
+in a couple seconds.
+
+## Acknowledgments
+
+I straight-up stole the design of the IO/network system from
+[Maelbreaker](https://github.com/rafibayer/maelbreaker/), which allowed me to get a working RPC
+call. Thanks!
+
+
+## TODO
+
+ - add error handling.